The UN refugee agency (UNHCR) said the first trucks arrived in a convoy of 49 vehicles.

"The first four trucks, carrying essentials including blankets and food packages of rice, oil and lentils were allowed into the town, where volunteers began unloading them in the dark, watched by groups of hungry people, including children," the agency said.

The operation to distribute aid was expected to take a few days, the spokesperson for the Red Cross delegation in Syria, Marianne Gasser, said.

"This is a very positive development. But it must not be just a one-off distribution. To relieve the suffering of these tens of thousands of people, there has to be regular access to these areas," she said.

Mousa al-Maleh, the head of the local committee in Madaya, told Al Jazeera that the amount of aid delivered was less than what is needed.

"The amount of items that have arrived on these trucks are too little and will not be enough to last long. This is a joke. I call on the international community to help end this siege and help the people of Madaya," he said.